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7emeraldempre
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An equalizer (or EQ) is a circuit used to adjust the frequency response of an input audio
signal. Develop an equalizer circuit that takes an audio output (for instance, from a Fender
Stratocaster electric guitar) and provides manually-controlled EQ (boost or attenuation) to
adjust the amplitude of two channels: bass (20 1000 Hz) and treble (1 kHz 20 kHz).
The output of the EQ circuit must provide sucient amplication to supply 125mW to a
speaker.
As with the previous project, you are restricted to using discrete transistors, diodes, and
other passive lumped components. You may not use packaged integrated circuits (such as
logic gates or operational ampliers).
To complete this project you are expected to develop a plan of attack with your lab partners
and to do the necessary background research required to successfully complete the work.
What my lab partners and I did
We do no know the impedence of the guitar my professor is going to use. We decided that a
buffer (an emitter follower) would be best to take care of that. We tried to get 1mA across the
emiiter, and I think we have it but I am not sure.
The next element in our design is a James Baxandall passive tone control network. We actually have one that works but not for the values that are specified in the lab document. (Normally, my two partners do analysis and I build. They attempt to build and I attempt analysis, but I am not strong with analysis and they never build until they do analysis. Thi causes us to have circuits that work but not for the values we should have. I litterally just pick random resistors and capacitors out of my shoebox and put them together. I learned a lot that way and have some interesting lab sessions.)
The tone control network is followed by the amplifier (a common emitter). There is real analysis for this part. We have a gain of 2 but we need a gain of 10.
The amplifier then goes to a push pull which goes to the speaker.
All the work that we have done is in the attachment withichis soon to follow.
*The analysis we did said to use a 6k resistor but we got some clipping. We chose random resistors until we got one with no clipping (we used the 1.8k, which the resistor we used to give us the gain of 2)
signal. Develop an equalizer circuit that takes an audio output (for instance, from a Fender
Stratocaster electric guitar) and provides manually-controlled EQ (boost or attenuation) to
adjust the amplitude of two channels: bass (20 1000 Hz) and treble (1 kHz 20 kHz).
The output of the EQ circuit must provide sucient amplication to supply 125mW to a
speaker.
As with the previous project, you are restricted to using discrete transistors, diodes, and
other passive lumped components. You may not use packaged integrated circuits (such as
logic gates or operational ampliers).
To complete this project you are expected to develop a plan of attack with your lab partners
and to do the necessary background research required to successfully complete the work.
What my lab partners and I did
We do no know the impedence of the guitar my professor is going to use. We decided that a
buffer (an emitter follower) would be best to take care of that. We tried to get 1mA across the
emiiter, and I think we have it but I am not sure.
The next element in our design is a James Baxandall passive tone control network. We actually have one that works but not for the values that are specified in the lab document. (Normally, my two partners do analysis and I build. They attempt to build and I attempt analysis, but I am not strong with analysis and they never build until they do analysis. Thi causes us to have circuits that work but not for the values we should have. I litterally just pick random resistors and capacitors out of my shoebox and put them together. I learned a lot that way and have some interesting lab sessions.)
The tone control network is followed by the amplifier (a common emitter). There is real analysis for this part. We have a gain of 2 but we need a gain of 10.
The amplifier then goes to a push pull which goes to the speaker.
All the work that we have done is in the attachment withichis soon to follow.
*The analysis we did said to use a 6k resistor but we got some clipping. We chose random resistors until we got one with no clipping (we used the 1.8k, which the resistor we used to give us the gain of 2)
Attachments
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